A mathematical model is developed for the analysis of spatially varied steady flow in irrigation canals. The model accounts for canal seepage and effect of control structures at the upstream and downstream ends of the canal. Two computational methods developed to solve the spatially varied steady flow equations for the irrigation canals are presented here. The governing differential equations are solved iteratively using fourth order explicit Runge-Kutta method. The model results are verified with experimentally observed water surface profiles available in literature. The effects of bed seepage, canal condition and backwater curves on the discharge carrying capacity and variation of flow depth are studied through model application on a canal reach. It is found, that in most of the situations the backwater curves spread sufficiently upstream and significantly affect the performance of the control structure at the upstream end. In many situations, it may not even be possible to operate the canal at design discharges.